I think it's a different computer altogether since the LT1 has 8 seperate injectors while the L03 has two. Also, the L03 doesn't have a MAF so it's probably lacking the wiring and chips for it.
If you're getting the LT1 together with the 4L60E tranny you'll need the wiring for that (91 caprices come with the non-electronic 4L60)
I would try to get the computer with the LT1 you are buying.
Also, try reposting this in the Engine Performance section, that forum has a lot of posts about engine swaps.
Keep me posted of your progress please, I have been thinking about doing an LT1 swap myself.